1: # include   "../ingres.h"
   2: # include   "../tree.h"
   3: # include   "../symbol.h"
   4: 
   5: /* DECOMP3 -- This file contains routines associated with redefining
   6: **	attribute numbers. This is needed when one variable sub queries
   7: **	or reduction change the positions of attributes in a relation.
   8: **	This file includes:
   9: **
  10: **	Tempvar -- Change the attribute numbers to new ones.
  11: **
  12: **	Origvar -- Restore attribute numbers back to their previous values.
  13: **
  14: **	Ckvar   -- Return the currently active VAR node
  15: */
  16: 
  17: 
  18: 
  19: tempvar(node, sqlist, buf)
  20: struct querytree    *node;
  21: struct querytree    *sqlist[];
  22: char            *buf;
  23: 
  24: /*
  25: ** Tempvar -- Replace a VAR attribute number with its new number.
  26: **
  27: **	Tempvar is given a list of subqueries which will potentially
  28: **	alter the attribute numbers of VARs they reference. An attno
  29: **	is changed by making the current VAR point to a new VAR node
  30: **	which has the updated attno.
  31: **
  32: **	The new attno is determined from the target list of the subquery
  33: **	for that VAR. The RESDOM number is the new attno and the VAR it
  34: **	points to is the old attno. For example:
  35: **		RESDOM/2 -> right = VAR 1/3
  36: **	The right subtree of result domain 2 is domain 3 of variable 1.
  37: **	Thus domain 3 should be renumbered to be domain 2.
  38: */
  39: 
  40: {
  41:     register struct querytree   *v, *sq, *nod;
  42:     int             attno;
  43:     struct querytree        *ckvar(), *need();
  44: 
  45:     if ((nod = node) == NULL)
  46:         return;
  47: 
  48:     if (nod->sym.type == VAR )
  49:     {
  50:         nod = ckvar(nod);
  51:         if (sq = sqlist[((struct qt_var *)nod)->varno])
  52:         {
  53:             /* This var has a subquery on it */
  54: 
  55:             /* allocate a new VAR node */
  56:             if (buf)
  57:             {
  58:                 v = (struct querytree *) (((struct qt_var *)nod)->valptr = (char *) need(buf, 12));
  59:                 v->left = v->right = (struct querytree *) (((struct qt_var *)v)->valptr = (char *) 0);
  60:                 bmove(&nod->sym, &v->sym, 6);
  61:                 ((struct qt_var *)nod)->varno = -1;
  62:             }
  63:             else
  64:                 v = nod;
  65: 
  66:             /* search for the new attno */
  67:             for (sq = sq->left; sq->sym.type != TREE; sq = sq->left)
  68:             {
  69:                 if (((struct qt_var *)ckvar(sq->right))->attno == ((struct qt_var *)nod)->attno)
  70:                 {
  71: 
  72:                     ((struct qt_var *)v)->attno = ((struct qt_res *)sq)->resno;
  73: #					ifdef xDTR1
  74:                     if (tTf(12, 3))
  75:                     {
  76:                         printf("Tempvar:");
  77:                         writenod(nod);
  78:                     }
  79: #					endif
  80: 
  81:                     return;
  82:                 }
  83:             }
  84:             syserr("tempvar:dom %d of %s missing", ((struct qt_var *)nod)->attno, rangename(((struct qt_var *)nod)->varno));
  85:         }
  86:         return;
  87:     }
  88: 
  89:     tempvar(nod->left, sqlist, buf);
  90:     tempvar(nod->right, sqlist, buf);
  91: }
  92: 
  93: 
  94: 
  95: 
  96: origvar(node, sqlist)
  97: struct querytree    *node;
  98: struct querytree    *sqlist[];
  99: 
 100: /*
 101: ** Origvar -- Restore VAR node to previous state.
 102: **
 103: **	Origvar undoes the effect of tempvar. All vars listed
 104: **	in the sqlist will have their most recent tempvar removed.
 105: */
 106: 
 107: {
 108:     register struct querytree   *t;
 109:     register int            v;
 110: 
 111:     t = node;
 112:     if (!t)
 113:         return;
 114:     if (t->sym.type == VAR && ((struct qt_var *)t)->varno < 0)
 115:     {
 116:         for (; ((struct qt_var *)((struct qt_var *)t)->valptr)->varno<0; t=(struct querytree *)(((struct qt_var *)t)->valptr));
 117:         if (sqlist[v=((struct qt_var *)((struct qt_var *)t)->valptr)->varno])
 118:         {
 119:             ((struct qt_var *)t)->varno = v;
 120:             ((struct qt_var *)t)->valptr = 0;
 121:         }
 122:         return;
 123:     }
 124:     origvar(t->left, sqlist);
 125:     origvar(t->right, sqlist);
 126: }
 127: 
 128: 
 129: 
 130: struct querytree *ckvar(node)
 131: struct querytree *node;
 132: 
 133: /*
 134: ** Ckvar -- Return pointer to currently "active" VAR.
 135: **
 136: **	This routine guarantees that "t" will point to
 137: **	the most current definition of the VAR.
 138: */
 139: 
 140: {
 141:     register struct querytree   *t;
 142: 
 143:     t = node;
 144:     if (t->sym.type != VAR)
 145:     {
 146:         syserr("ckvar: not a VAR %d", t->sym.type);
 147:     }
 148:     while (((struct qt_var *)t)->varno < 0)
 149:         t = (struct querytree *)(((struct qt_var *)t)->valptr);
 150:     return(t);
 151: }
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